Interesting observation on the cyclic wiggle...It is conceivable that the cyclic motion is affecting the local flow in the downwash that affects the tail rotor, as otherwise, the torque demand would rise for steady rotor height. Am curious if there is a known reason why cyclic motion would improve TR effectiveness. It may be that the cyclic gives also a slight overspeed condition through the hysteresis of the governor, which would give increased TR authority.
I think it was just the change in downwash. With that little wiggle and it disturbs whatever is building up around the tail rotor.
For the overspeed condition, I don't think so. The governor of the R22 wasn't very fast. When you are flying with a steady power setting like in that slow flight, I never felt a lot of movement in the twist grip.